Compressed audio signals are signals which have undergone some form of data compression by a perceptual audio codec. Perceptual audio codecs reduce the amount of data used to store, transfer, or transmit an audio signal by discarding components of the audio signal that are perceived to be less audible or less perceptually important. The data compression process often introduces undesirable audible differences between the original (uncompressed) audio signal and the compressed audio signal. Different perceptual audio codecs may employ different strategies for discarding portions of the original audio signal, but the perceived characteristics of the audible differences are typically similar.